S. M. Azhari; M. Rezapour; A. A. Mottaghi
Abstract
Northeastern part of Iran islocated in the Kopeh Dagh seismotectonic province. This province is part of the Alpine-Himalayan orogenic belt. In the last two decades, a number of earthquakes occurred in this region. Therefore, investigating and relocating these earthquakes with adequate precise play a ...
Read More
Northeastern part of Iran islocated in the Kopeh Dagh seismotectonic province. This province is part of the Alpine-Himalayan orogenic belt. In the last two decades, a number of earthquakes occurred in this region. Therefore, investigating and relocating these earthquakes with adequate precise play a great role in seismicity research of the study area. Adequate crustal structure velocity has a key role in relocating the earthquakes. Since the earthquakes in this region are shallow earthquakes, the upper part of crustal structure can be acquired. So in this study, Mashhad and Quchan seismological networks data were used to determine the crustal structure velocity. In order to determine the velocity structure, Vp/Vs was first determined using the methods of Wadati and travel time of1.72 .Then by applying various filters and selection of several earthquakes 1D velocity structure of the arrival times was determined. Results reveal two velocity discontinuities approximately at 4 and 14 km depths. The resulting model consists of a 4-km-thick layer with VP = 5.9 kms−1 overlying a 10-km-thick layer with VP = 6.17 kms−1. Then the initial 1D velocity model was used to determine the three-dimensional velocity structure using LOTOS code. The results show significant changes in the vicinity of Mashhad. Two zones with higher velocity are observed in the north and south of Mashhad due to Kashaf Roud and Binaloud Faults. In the north of Mashhad, a change in velocity is observed, which might be due to the Tous fault. In the south of Mashhad, a sharp velocity discontinuity at the depth of 4 km is probably due to an alluvium cover above a bedrock of varying thickness. Also, the tomography results indicate that the area of Shandiz fault system in the south of Mashhad is associated with a lower velocity zone compared to its adjacent areas.
R Samadi; N Sh; H Kawabata
Abstract
Plutonic suite of Khajeh Morad at southeast of Mashhad includes granodiorites, which are cut across by younger aplite, granitic pegmatite dykes and monzogranites. Aplites are mineralogically including quartz, feldspar (albite to orthoclase and microcline), muscovite, and accessory minerals of garnet ...
Read More
Plutonic suite of Khajeh Morad at southeast of Mashhad includes granodiorites, which are cut across by younger aplite, granitic pegmatite dykes and monzogranites. Aplites are mineralogically including quartz, feldspar (albite to orthoclase and microcline), muscovite, and accessory minerals of garnet (almandine-spessartine), tourmaline, biotite, and ilmenite. Pegmatites are composed of quartz, feldspar (albite to oligoclase, orthoclase, and microcline), muscovite, and minor amounts of garnet (almandine-spessartine), tourmaline, ilmenite, beryl, and columbite. Based on mineralogical and geochemical evidence, Khajeh Morad pegmatites are related to Li-rare elements (RE-Li) and lithium-cesuim-tantalum (LCT) pegmatite family. According to the field evidence and whole rock geochemistry, origin of garnet-bearing aplite-pegmatite melts could be related to the S-type monzogranites, as their differentiation products at late stages, occurred in a continental collision belts.
R Samadi; H Mirnejad; A.A Baharifar; S.J Sheikh Zakariaee
Abstract
The fibrolite garnet staurolite mica schist and staurolite garnet mica schist cropped out around the northwest of Khalaj, south of Mashhad in a SE_NW direction along the metamorphic complex of Kuh-e-Majuni. They have similar mineralogy and consist of quartz, annite, staurolite, almandine, muscovite, ...
Read More
The fibrolite garnet staurolite mica schist and staurolite garnet mica schist cropped out around the northwest of Khalaj, south of Mashhad in a SE_NW direction along the metamorphic complex of Kuh-e-Majuni. They have similar mineralogy and consist of quartz, annite, staurolite, almandine, muscovite, zircon, and ilmenite; however, fibrolite in fibrolite garnet staurolite mica schist, and chlorite and tourmaline in the staurolite garnet mica schist are additionally found. Application of garnet - biotite thermometry and GBMAQ barometry indicates the temperatures and pressures of 560 and 605 °C / 3.5 and 5 kilobar for fibrolite garnet staurolite mica schist and temperatures of 489 and 547 °C (in 3.5 to 5 kilobar) for the staurolite garnet mica schist. Pressure and temperature increasing during the garnet growth indicates the effect of regional and contact thermal metamorphism on these rocks. Based on mineral paragenesis in KFMASH system, the metamorphic degree of regional metamorphism was about lower amphibolite (in staurolite garnet mica schist) to middle amphibolite facies (in fibrolite garnet staurolite mica schist). Meanwhile, intrusion of the Khalaj granitoid and its thermal diffusion raised the metamorphic temperature up to lower amphibolite facies (in staurolite garnet mica schist) and middle amphibolite facies (in fibrolite garnet staurolite mica schist), and consequently, this caused the fibrolite formation in the sample close to the pluton (i.e. fibrolite garnet staurolite mica schist).
F Behravesh; M.H Mahmudy Gharaie; F Ghassemzadeh; S Avaz Moghaddam
Abstract
Traffic dust often contains high concentrations of heavy metals and can influence on environment and human health. In this study, we tried to measure heavy metals in street dusts and soil in the city of Mashhad and sample collections were carried out at the time and location of high traffic. For the ...
Read More
Traffic dust often contains high concentrations of heavy metals and can influence on environment and human health. In this study, we tried to measure heavy metals in street dusts and soil in the city of Mashhad and sample collections were carried out at the time and location of high traffic. For the purpose of this study, twenty three samples were collected from three main paths that cover the entire city and total concentrations of five heavy metals (Ni, Zn, Pb, Cr, and Cu) were measured. The index of geo-accumulation (Igeo), Pollution index (PI) and integrated pollution index (IPI) were also calculated for the contamination levels of the metals in the city of Mashhad,. The pollution index represent that all samples are highly polluted by Pb (3.688-74.16) and most of the samples are highly polluted by Zn (1.484-7.23). However, Cu (0.678-1.945) and Ni show medium level of pollution in the samples (1.01-1.935). Chromium in all samples show low levels of contamination (0.246-0.772). Possible sources of the pollutants were assessed using Pearson correlation and principal components analysis. The results of this analysis show high concentrations of metals such as lead, copper, zinc and nickel in the soil samples as compared to UCC (Upper Continental Crust). There is a positive correlation between heavy metals of zinc and copper as well as lead and zinc, which indicate the source of these metals, can be fuels as well as powder of shoe brake of vehicles. The results of the sequential extraction procedure also imply that the elements of Ni, Zn and Pb has occurred in unstable phases (F1+F2+F3+F4), indicating their human origin. But the elements such as Cr and Cu are mainly on stable phases (F5), which represents natural origin for these two elements.
A Ghazi; N Hafezi Moghadas; H Sadeghi; M Ghafoori; G Lashkaripour
Abstract
In this study, engineering geomorphology of MashhadCity is evaluated. For this purpose, aerial photos of the city, 180 drinking water wells and 1500 scattered geotechnical boreholes have been studied. Based on this information, the city divided into 6 geomorphologic units including rock outcrop, pediment, ...
Read More
In this study, engineering geomorphology of MashhadCity is evaluated. For this purpose, aerial photos of the city, 180 drinking water wells and 1500 scattered geotechnical boreholes have been studied. Based on this information, the city divided into 6 geomorphologic units including rock outcrop, pediment, Golestan fan, Torough fan, southern fans and flat plain. Then, engineering geology properties of these units were investigated based on the geotechnical data sets. The geotechnical properties were evaluated just for the upper 10m of deposits. The results show predominant soil in the pediment and southern fans units is gravel, sandy and gravely soils are predominant in the Golestan fan unit, whereas clay and sand are predominant soils in the Torough fan and flat plain. In this study, earth evaluation was carried out based on the standard penetration test that shows the pediment unit has more resistance than other units. The clay minerals were determined based on the activity chart. Smectite and kaolinite are predominant clay minerals in the pediment and flat plain units, respectively.
Ramin Samadi; M. V. Valizadeh; H. Mirnejad; H. Kawabata
Abstract
Metamorphic rocks of Dehnow area mainly consist of gray to black fine-grained schists. Garnet schists are closer to the tonalitic body than the garnet chloritoid schists. There is a thin layer of staurolite and andalusite bearing hornfels between these schists and the Dehnow tonalitic body. Garnet schists ...
Read More
Metamorphic rocks of Dehnow area mainly consist of gray to black fine-grained schists. Garnet schists are closer to the tonalitic body than the garnet chloritoid schists. There is a thin layer of staurolite and andalusite bearing hornfels between these schists and the Dehnow tonalitic body. Garnet schists and garnet chloritoid schists of Dehnow area are mineralogically comprised of quartz, biotite, muscovite, garnet, chlorite, chloritoid, tourmaline and ilmenite. Geothermobarometry results indicate that hornfels (550oC, 4.3 kbar) and garnet chloritoid schist (486-497oC) have formed in lower equilibrium condition in comparison with garnet schist (569oC, 5.3 kbar).
